The aim of this thesis was to examine the satisfaction of biology teachers in high school programs with the concept, understanding and implementation of the valid curriculum in teaching and understanding of the conceptual approach in teaching biology. Significant differences between the answers of teachers with different length of work experience as well as the influence of the length of work experience on teachers' answers were examined. An online questionnaire was designed and sent to biology teachers via the Education and Teacher Training Agency. 78 teachers filled out the questionnaire. The results of the survey indicate that teachers often encounter difficulties in understanding the conceptual approach and educational outcomes, as well as difficulties in assessing the depth of the teaching content. No significant differences were observed between the answers of teachers with different length of work experience, nor a significant influence of the length of work experience on teachers' answers. However, it was observed that teachers with more than 11 years of work experience express greater dissatisfaction with the current curriculum. It can be concluded that teachers recognize the potential of teaching biology based on student-centered active learning methods; however, according to the teachers’ responses, the current curriculum only partially fulfills the intended learning outcomes and teachers' expectations in practice. Therefore, it would be beneficial to enable a regular reevaluation of the curriculum that would take into account the teacher's review, as well as constant systematic support for teachers, so that they can navigate more successfully in achieving the educational goals of the teaching process.